OAKLAND — Luke Walton didn’t have to interview with Steve Kerr this summer to become the Warriors’ lead assistant coach and run the top-scoring offense in the NBA.

“Steve just called and said he wanted to promote me, so obviously he showed a lot of the confidence that he had in me,” Walton said.

Kerr called Walton again early Thursday morning with news of another shift in the coaching staff. Kerr had decided to take a leave of absence to focus on rehabilitation after two offseason back surgeries.

With that, the 35-year-old Walton became interim head coach of the defending NBA champions. He’s expected to be the one sitting in the lead chair when the Warriors play their preseason opener against the Toronto Raptors at SAP Center on Monday.

At this time a year ago, Walton had yet to coach a single NBA game.

“Isn’t that how it’s supposed to happen?” Walton said, smiling. “Retire, win a championship, lead assistant and then interim head coach.”

Walton is only two years removed from a 10-year NBA playing career highlighted by helping the Los Angeles Lakers win back-to-back championships. He’s young enough to have been a college teammate to Andre Iguodala at the University of Arizona.

But after Kerr gave a fellow Arizona alum an assistant coaching position last season, Walton was impressive. Warriors general manager Bob Myers and forward Draymond Green volunteered recently in separate interviews that Walton possesses “a brilliant basketball mind.”

Walton, the son of Hall of Famer Bill Walton, had plenty of positive influences growing up in the game. His father would write John Wooden quotes on his lunch bags. He starred at Arizona for Hall of Fame coach Lute Olson. Phil Jackson, who taught the triangle offense, was the coach for seven of the seasons that the 6-foot-8 Walton played for the Lakers.

“Luke is one of these people who was born with an innate understanding of the game of basketball, and he’s respected,” Myers said.

Said Green: “Sometimes you may be thinking something that everybody else may not see. But if you go to Luke and talk to him, he knows exactly what you’re talking about.

“I think it’s one of those things that you just can’t teach. Like he’s that type of basketball smart.”

With a baritone voice like his father’s, Walton also won the respect of the Warriors’ players with his ability to communicate. As an assistant last season, he helped players understand Kerr’s vision. With Alvin Gentry leaving for the New Orleans Pelicans and Kerr stepping aside, Walton will have even greater responsibilities.

“Players expect honesty, and as long as we have a relationship and they feel that I’m not trying to get anything over on them, I can be laid-back, and then I can still pull them aside and tell them that they’re messing up, that they need to do something better. They respect it, and they respond to it.

“The guys know that … if I see laziness happening or we’re not playing at a certain level, it’s my job without Steve here to step up. And I’d be cheating them and cheating our team if I didn’t say anything.”

Unlike an ailing Kerr, Walton was able to recharge in the offseason.

Before gaining experience as a head coach for the first time with the Warriors’ summer league team that went 3-3 in Las Vegas, he was backstage attending the Grateful Dead concert at Levi’s Stadium with his Deadhead father.

In August, Walton played on a six-man beach volleyball team based on the cult comedy movie “Fletch” and won the tournament title. The following week, the still recognizable Walton allowed for a TMZ interview to be conducted on a jet bridge and answered questions about his fantasy football draft in Las Vegas.

“I think it’s good to get out,” Walton said. “It’s good for the mind to do different things and not just be in the gym all the time. We know what we need to accomplish, and I know the game of basketball. Before training camp until after the year, there’s no volleyball or golf happening for me. It’s all work, and that’s getting the team to where we need to be.”